A comparative study among catalytic wet air oxidation, Fenton, and Photo-Fenton technologies for the on-site treatment of hospital wastewater

Abstract

The feasibility of catalytic wet air oxidation, intensified homogeneous Fenton and heterogeneous Photo-Fenton systems for the treatment of real hospital wastewater has been investigated. Wastewater samples were collected from a hospital sewer, during a weekly monitoring program, and fully characterized. Up to seventy-nine pharmaceuticals, including mostly parent compounds and some of their transformation products, were analyzed. Catalytic wet air oxidation allowed the complete removal of several pharmaceutical groups, but it did not allow to eliminate analgesics/anti-inflammatories and antibiotics, whose average removal was around 85%. Intensified Fenton oxidation was the most efficient process for all the drugs removal with an almost complete reduction of the initial pharmaceutical load (99.8%). The heterogeneous Photo-Fenton system reached a 94.5% reduction of the initial pharmaceutical load. The environmental risk of the treated samples by the hazard quotient (HQ) method was also evaluated. Fenton oxidation was the most effective system with a final ∑HQ of 5.4. Catalytic wet air oxidation and Photo-Fenton systems achieved total ∑HQ values of 895 and 88, respectively. This fact was related to the presence of refractory antibiotics in the treated catalytic wet air oxidation samples. On the opposite, the Photo-Fenton system provided the elimination of most pharmaceutical pollutants that pose a high environmental risk such as antibiotics. Simplified cost estimation was finally performed as a preliminary approach of the economy of the three oxidation processes for the hospital wastewater treatment.